Commercial pool filtration systems must be able to control a wide range of operating conditions or filtration cycles. Each filtration cycle is subject to a large number of operational changes dependent upon the pump used, filter type, flow rate, and environmental conditions. In applications such as commercial pool filtration systems there are requirements mandated by local building codes for minimum pump flow rates in order to provide adequate filtration.
The pump's primary design point is selected to operate against the most demanding condition in the filtration cycle, that is the dirtiest filtration point which occurs just prior to a pool backwash. The water circulation pump is selected to operate at the design point as efficiently as possible. Unfortunately, when pool filters are clean the pump operates against a total head of 10 PSI to 15 PSI which is less than the primary design point. This condition results in the pump operating for extended periods of time at an inefficient position on its performance curve and may result in damaging cavitation. Cavitation is the sudden formation and collapse of low pressure bubbles in liquid by means of mechanical forces. Cavitation not only causes the pump to under perform but is also very damaging to the pump's impeller and other internal components which can shorten the pump's useful life.
The instant invention maintains an optimum water flow rate by adjusting the speed of the pump to match the loads that vary throughout the filter cycle. In doing so it keeps the overall pump performance within the most efficient area of operation which saves energy, and results in less wear and tear, increases the reliability and extends the useful life of the pump. The invention also has other special energy saving features of operation that allow the pump to be slowed or stopped during pool-closure hours.
A search of the prior art did not disclose any literature or patents that read directly on the claims of the instant invention. However, the following U.S. patents are considered related:
U.S. PAT. NO.INVENTORISSUED7,156,983Burrey2 Jan. 20075,730,861Sterghos et al24 Mar. 19984,676,914Mills et al30 Jun. 19874,505,643Millis et al19 Mar. 1985
The U.S. Pat. No. 7,156,983 patent discloses a swimming pool backwash control system that includes a timer and a valve combination that controls normal re-circulating and backwash flow through a swimming pool filter. The timer is in series with an electric power circuit that activates the pool pump when the valve is moved to the backwash flow position. The timer also maintains the electric power to the pump for a user-specified or a pre-set period. At the end of the period the timer causes the circuit to open, thereby disabling the pump. Power can be restored to the pump by returning the valve to its normal re-circulating flow position.
The U.S. Pat. No. 5,730,861 patent discloses a swimming pool control system that automatically controls the daily maintenance functions of a swimming pool. The control system monitors system conditions, makes adjustments for abnormal conditions, and provides remote feedback of system problems during its daily cycle.
The U.S. Pat. No. 4,676,914 patent discloses a pump that pumps water from a swimming pool to a forward/reverse direction control valve. The control valve has a forward flow state in which it channels water into an inlet of a filter and from a filter outlet back to the swimming pool.
The U.S. Pat. No. 4,505,643 patent discloses a circulating pump that pumps water between a swimming pool and a filter or other circulated fluid receiving apparatus. A control circuit operates the circulating pump and includes a first timer and a cycle switch which is cyclically closed to produce a pump signal for a first duration that starts a second timer. The second timer holds a time controlled switch conductive for a pre-selected time period. When the pressure monitored by a pressure sensor exceeds a pre-selected pressure, a low pressure switch closes conducting the pump signal around the bypass and time controlled switches.
For background purposes and as indicative of the art to which the invention relates, reference may be made to the following remaining patents found in the search:
U.S. PAT. NO.INVENTORISSUED5,895,565Steininger, et al20 Apr. 19995,584,992Sugimoto17 Dec. 19964,482,461Hindman, et al13 Nov. 19843,963,375Curtis15 Jun. 19763,365,064Horan23 Jan. 1968